/***************************************************************************
 * ncat_lua.c -- ncat lua facilities                                       *
 ***********************IMPORTANT NMAP LICENSE TERMS************************
 *
 * The Nmap Security Scanner is (C) 1996-2025 Nmap Software LLC ("The Nmap
 * Project"). Nmap is also a registered trademark of the Nmap Project.
 *
 * This program is distributed under the terms of the Nmap Public Source
 * License (NPSL). The exact license text applying to a particular Nmap
 * release or source code control revision is contained in the LICENSE
 * file distributed with that version of Nmap or source code control
 * revision. More Nmap copyright/legal information is available from
 * https://nmap.org/book/man-legal.html, and further information on the
 * NPSL license itself can be found at https://nmap.org/npsl/ . This
 * header summarizes some key points from the Nmap license, but is no
 * substitute for the actual license text.
 *
 * Nmap is generally free for end users to download and use themselves,
 * including commercial use. It is available from https://nmap.org.
 *
 * The Nmap license generally prohibits companies from using and
 * redistributing Nmap in commercial products, but we sell a special Nmap
 * OEM Edition with a more permissive license and special features for
 * this purpose. See https://nmap.org/oem/
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 * If you have received a written Nmap license agreement or contract
 * stating terms other than these (such as an Nmap OEM license), you may
 * choose to use and redistribute Nmap under those terms instead.
 *
 * The official Nmap Windows builds include the Npcap software
 * (https://npcap.com) for packet capture and transmission. It is under
 * separate license terms which forbid redistribution without special
 * permission. So the official Nmap Windows builds may not be redistributed
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 *
 ***************************************************************************/

/* $Id$ */

#include "ncat.h"
#include "ncat_lua.h"

static lua_State *L;
static int last_function_number;

static void report(char *prefix)
{
    const char *errormsg;
    errormsg = lua_tostring(L, -1);
    if (errormsg == NULL)
        errormsg = "(error object is not a string)";
    bye("%s: %s.", prefix, errormsg);
}

static int traceback (lua_State *LL)
{
    const char *msg;
    msg = lua_tostring(LL, 1);
    if (msg) {
        luaL_traceback(LL, LL, msg, 1);
    } else {
        if (!lua_isnoneornil(LL, 1)) {  /* is there an error object? */
            if (!luaL_callmeta(LL, 1, "__tostring"))  /* try its 'tostring' metamethod */
                lua_pushliteral(LL, "(no error message)");
        }
    }
    return 1;
}

void lua_setup(void)
{
    ncat_assert(o.cmdexec != NULL);

    L = luaL_newstate();
    luaL_openlibs(L);

    if (luaL_loadfile(L, o.cmdexec) != 0)
        report("Error loading the Lua script");

    /* install the traceback function */
    last_function_number = lua_gettop(L);
    lua_pushcfunction(L, traceback);
    lua_insert(L, last_function_number);
}

void lua_run(void)
{
    if (lua_pcall(L, 0, 0, last_function_number) != LUA_OK && !lua_isnil(L, -1)) {
        /* handle the error; the code below is taken from lua.c, Lua source code */
        lua_remove(L, last_function_number);
        report("Error running the Lua script");
    } else {
        if (o.debug)
            logdebug("%s returned successfully.\n", o.cmdexec);
        lua_close(L);
        exit(EXIT_SUCCESS);
    }
}
